package vn.conghuy.talkwithme.android.utils;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

public class DatabaseHelper extends SQLiteOpenHelper {
	
	private static DatabaseHelper instance = null;
	
	public static DatabaseHelper GetInstanceAndInit(Context context)
	{
		if(instance == null)
		{
			instance = new DatabaseHelper(context);
		}
		return instance;
	}
	
	public static DatabaseHelper GetInstance()
	{
		return instance;
	}
	
	/**
	 * @uml.property  name="context"
	 * @uml.associationEnd  
	 */
	Context context;
	/**
	 * @uml.property  name="myDataBase"
	 * @uml.associationEnd  
	 */
	private SQLiteDatabase myDataBase; 
	
	static final String DB_NAME = "talkwithme.db";
	private static String DB_PATH = "/data/data/vn.conghuy.talkwithme/databases/";
	
	private DatabaseHelper(Context context){
		super(context, DB_NAME, null, 33);
		this.context = context;
	}
	
	private void createDataBase() throws IOException{
		 
	    boolean dbExist = checkDataBase();
	 
	    if(dbExist){
    		//do nothing - database already exist
    	}else{
 
    		//By calling this method and empty database will be created into the default system path
               //of your application so we are gonna be able to overwrite that database with our database.
        	this.getReadableDatabase();
 
        	try {
    			copyDataBase();
    		} catch (IOException e) {
        		throw new Error("Error copying database");
        	}
    	}
    }
	 
    /**
     * Check if the database already exist to avoid re-copying the file each time you open the application.
     * @return true if it exists, false if it doesn't
     */
    private boolean checkDataBase(){
 
    	SQLiteDatabase checkDB = null;
 
    	try{
    		String myPath = DB_PATH + DB_NAME;
    		checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
    	}catch(SQLiteException e){
    		//database does't exist yet.
    	}
 
    	if(checkDB != null){
    		checkDB.close();
    	}
 
    	return checkDB != null ? true : false;
    }
 
    /**
     * Copies your database from your local assets-folder to the just created empty database in the
     * system folder, from where it can be accessed and handled.
     * This is done by transfering bytestream.
     * */
    private void copyDataBase() throws IOException{
 
    	//Open your local db as the input stream
    	InputStream myInput = context.getAssets().open(DB_NAME);
 
    	// Path to the just created empty db
    	String outFileName = DB_PATH + DB_NAME;
 
    	//Open the empty db as the output stream
    	OutputStream myOutput = new FileOutputStream(outFileName);
 
    	//transfer bytes from the inputfile to the outputfile
    	byte[] buffer = new byte[1024];
    	int length;
    	while ((length = myInput.read(buffer))>0){
    		myOutput.write(buffer, 0, length);
    	}
 
    	//Close the streams
    	myOutput.flush();
    	myOutput.close();
    	myInput.close();
 
    }
 
    private void openDataBase() throws SQLException{
 
    	//Open the database
        String myPath = DB_PATH + DB_NAME;
    	myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
 
    }
    
    public void startDatabase()
    {
    	try {
			createDataBase();
        } catch (IOException e) {
			Log.e("MY", "Cannot create database");
        }
        
        openDataBase();
    }
 
    @Override
	public synchronized void close() {
 
    	    if(myDataBase != null)
    		    myDataBase.close();
 
    	    super.close();
 
	}
 
	@Override
	public void onCreate(SQLiteDatabase db) {
 
	}
 
	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
 
	}
	
	public Cursor ExecuteQuery(String query)
	{
		if(myDataBase != null)
		{
			return myDataBase.rawQuery(query, null);
		}else{
			Log.i("MY", "Haven't start database yet.");
			return null;
		}
	}
	
	public void ExecuteNonQuery(String query)
	{
		if(myDataBase != null)
		{
			myDataBase.rawQuery(query, null);
		}else{
			Log.i("MY", "Haven't start database yet.");
		}
	}

}

